From: Tuan Do <tuan@calif.io> mainline inclusion from mainline-v7.1-rc1 commit f8dca15a1b190787bbd03285304b569631160eda category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/14407 CVE: CVE-2026-31665 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- nft_ct_timeout_obj_destroy() frees the timeout object with kfree() immediately after nf_ct_untimeout(), without waiting for an RCU grace period. Concurrent packet processing on other CPUs may still hold RCU-protected references to the timeout object obtained via rcu_dereference() in nf_ct_timeout_data(). Add an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer freeing until after an RCU grace period, matching the approach already used in nfnetlink_cttimeout.c. KASAN report: BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0 Read of size 4 at addr ffff8881035fe19c by task exploit/80 Call Trace: nf_conntrack_tcp_packet+0x1381/0x29d0 nf_conntrack_in+0x612/0x8b0 nf_hook_slow+0x70/0x100 __ip_local_out+0x1b2/0x210 tcp_sendmsg_locked+0x722/0x1580 __sys_sendto+0x2d8/0x320 Allocated by task 75: nft_ct_timeout_obj_init+0xf6/0x290 nft_obj_init+0x107/0x1b0 nf_tables_newobj+0x680/0x9c0 nfnetlink_rcv_batch+0xc29/0xe00 Freed by task 26: nft_obj_destroy+0x3f/0xa0 nf_tables_trans_destroy_work+0x51c/0x5c0 process_one_work+0x2c4/0x5a0 Fixes: 7e0b2b57f01d ("netfilter: nft_ct: add ct timeout support") Cc: stable@vger.kernel.org Signed-off-by: Tuan Do <tuan@calif.io> Signed-off-by: Florian Westphal <fw@strlen.de> Conflicts: include/net/netfilter/nf_conntrack_timeout.h net/netfilter/nft_ct.c [commit 6daf14140129 ("netfilter: Replace zero-length array with flexible-array member") is not backport, target uses 'char data[0]' instead of 'char data[]', need to insert struct rcu_head before data[0]. commit b184356d0a00 ("netfilter: conntrack: remove module owner field") is not backport, target still has nf_ct_l4proto_put(timeout->l4proto) in nft_ct_timeout_obj_destroy(), need to preserve it while replacing kfree with kfree_rcu.] Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- include/net/netfilter/nf_conntrack_timeout.h | 1 + net/netfilter/nft_ct.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/include/net/netfilter/nf_conntrack_timeout.h b/include/net/netfilter/nf_conntrack_timeout.h index 3394d75e1c80..d6f74145f945 100644 --- a/include/net/netfilter/nf_conntrack_timeout.h +++ b/include/net/netfilter/nf_conntrack_timeout.h @@ -14,6 +14,7 @@ struct nf_ct_timeout { __u16 l3num; const struct nf_conntrack_l4proto *l4proto; + struct rcu_head rcu; char data[0]; }; diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c index b17604b5b48b..2fc92f42cea6 100644 --- a/net/netfilter/nft_ct.c +++ b/net/netfilter/nft_ct.c @@ -906,7 +906,7 @@ static void nft_ct_timeout_obj_destroy(const struct nft_ctx *ctx, nf_ct_untimeout(ctx->net, timeout); nf_ct_l4proto_put(timeout->l4proto); nf_ct_netns_put(ctx->net, ctx->family); - kfree(priv->timeout); + kfree_rcu(priv->timeout, rcu); } static int nft_ct_timeout_obj_dump(struct sk_buff *skb, -- 2.43.0